Tetramorium smaug Hita, 2012

Hita Garcia, F. & B. L. Fisher, 2012, The ant genus Tetramorium Mayr (Hymenoptera: Formicidae) in the Malagasy region - taxonomic revision of the T. kelleri and T. tortuosum species groups., Zootaxa 3592, pp. 1-85 : 79-80

Tetramorium smaug Hita Garcia & Fisher sp. n.

(Figs. 27, 28, 138, 139, 140, 142)

Holotype worker, MADAGASCAR, Toamasina, Ambatovy, 12.4 km NE Moramanga, 18.83937 S, 48.30842 E, 1080 m, montane rainforest, pitfall trap, collection code BLF16917, 4.-7.V.2007 (B.L. Fisher et al.) (CASC: CASENT0121244). Paratype, one worker with same data as holotype (CASC: CASENT0124788).

Diagnosis

Tetramorium smaug can be easily discriminated from the remainder of the species complex by the following character set: antennal scapes comparatively short (SI 77-81); extremely long and massively constructed propodeal spines (PSLI 57-63); anterodorsal and posterodorsal margins of petiolar node situated at about same height; mesosoma with 7 to 14 pairs of standing hairs; hairs on leading edge of antennal scapes subdecumbent to suberect; first gastral tergite with several scattered standing hairs and very sparse, short, appressed pubescence; very dark brown to black colouration.

Description

HL 0.99-1.04 (1.02); HW 0.99-1.06 (1.02); SL 0.80-0.85 (0.81); EL 0.19-0.23 (0.21); PH 0.50-0.54 (0. 52); PW 0.70-0.77 (0.74); WL 1.30-1.38 (1.34); PSL 0.57-0.66 (0.60); PTL 0.30-0.38 (0.34); PTH 0.36-0.43 (0.40); PTW 0.25-0.32 (0. 29); PPL 0.30-0.32 (0.31); PPH 0.38-0.42 (0.41); PPW 0.36-0.41 (0.38); CI 100-102 (101); SI 77-81 (79); OI 19-22 (20); DMI 54-58 (56); LMI 38-40 (39); PSLI 57-63 (59); PeNI 35-41 (38); LPeI 77-91 (86); DPeI 79-88 (83); PpNI 48-55 (52); LPpI 73-79 (76); DPpI 120-132 (125); PPI 128-144 (135) (six measured).

Head as long as wide to weakly wider than long (CI 100-102); posterior head margin strongly concave. Anterior clypeal margin medially impressed. Frontal carinae strongly developed, diverging posteriorly, and ending at corners of posterior head margin. Antennal scrobes well-developed, moderately deep, but narrow and without defined posterior and ventral margins. Antennal scapes of moderate length, not reaching posterior head margin (SI 77-81). Eyes small to moderate (OI 19-22). Mesosomal outline in profile flat, moderately marginate from lateral to dorsal mesosoma; promesonotal suture and metanotal groove absent; mesosoma comparatively stout and high (LMI 38-40). Propodeal spines massively constructed with very broad base, extremely long, and acute (PSLI 57-63); propodeal lobes short and rounded. Petiolar node in profile rectangular nodiform, approximately 1.1 to 1.3 times higher than long (LPeI 77-91), anterior and posterior faces approximately parallel, anterodorsal and posterodorsal margins approximately at same height, dorsum slightly convex; node in dorsal view approximately 1.1 to 1.3 times longer than wide (DPeI 79-88). Postpetiole in profile subglobular, weakly anteroposteriorly compressed, approximately 1.2 to 1.4 times higher than long (LPpI 73-79); in dorsal view around 1.2 to 1.3 times wider than long (DPpI 120-132). Postpetiole in profile appearing less voluminous than petiolar node, in dorsal view approximately 1.3 to 1.5 times wider than petiolar node (PPI 128-144). Mandibles distinctly longitudinally rugose; clypeus longitudinally rugose, with three to five rugae; cephalic dorsum between frontal carinae with 9 to 12 longitudinal rugae, most rugae running unbroken from posterior head margin to anterior clypeus, few rugae interrupted or with cross-meshes; lateral and ventral head longitudinally rugose, rarely with cross-meshes. Mesosoma laterally and dorsally distinctly longitudinally rugose. Forecoxae with very distinct and pronounced longitudinal rugae. Waist segments longitudinally rugose, rugae on waist segments weaker than on head and mesosoma, especially dorsally. Gaster completely unsculptured, smooth, and shining. Ground sculpture generally faint to absent everywhere on body. Head with abundant standing hairs; mesosoma with 7 to 14 pairs of hairs; waist segments and first gastral tergite with few to several scattered, standing hairs; first gastral tergite with very sparse, short, and appressed pubescence. Anterior edges of antennal scapes with subdecumbent to suberect hairs. Body a uniform very dark brown to black colour.

Notes

The new species is currently only known from Ambatovy, Montagne d'Ambre, and Ivohibe. All three localities are montane rainforests at altitudes of 900 to 1300 m. However, these sites are geographically widely separated, one being located in the southeast, one in the east, and one in the northernmost tip of the island. This represents a fairly disjunctive distribution. Furthermore, the species is only known from six specimens, which could mean that it is very rare and uncommon, as seems to be the case with T. latreillei and T. sabatra. The scant available material was collected from pitfall traps, hand collecting, or rotten logs, which suggests that T. smaug is rarely encountered on the ground. As already stated in the description of T. sabatra, T. smaug might live in the vegetation, which could explain why it was only seldom sampled.

Within the T. smaug species complex, T. smaug cannot be mistaken for T. adamsi since the latter has a petiolar node with the posterodorsal margin situated higher than the anterodorsal margin. Also, it is unlikely to be confused with T. nazgul or T. marojejy because they are both much hairier than T. smaug. In addition, T. nazgul possesses the longest antennal scapes of the complex (SI 89-93) while the scapes of T. smaug are much shorter (SI 77-81). Moreover, T. marojejy differs also in body colour, which is orange to pale brown, whereas the body colour of T. smaug is very dark brown to black.

Tetramorium smaug is morphologically most closely associated with T. latreillei and T. sabatra. As mentioned above, the three species share the character combination of massive, extremely long propodeal spines, reduced hairiness, and very dark brown to back colouration. This character combination makes them unlikely to be confused with another species of the complex. Tetramorium smaug is also easily distinguished from T. latreillei and T. sabatra. Tetramorium latreillei has no standing hairs on the waist segments or the first gastral tergite, and displays moderately dense appressed pubescence on the first gastral tergite. This separates it clearly form T. sabatra and T. smaug. The latter two can also be easily distinguished from each other. Tetramorium smaug has 7 to 14 pairs of hairs throughout the mesosomal dorsum, whereas only one or two pairs are present in T. sabatra, and these are restricted to the pronotal dorsum. In addition, the hairs on the leading edge of the antennal scapes are generally strongly appressed in T. sabatra while they are subdecumbent to suberect in T. smaug.

As discussed in the descriptions of T. latreillei and T. sabatra, there is a possibility that T. smaug is conspecific with one or even both of them. The lack of material in all three species makes species delimitations difficult, although we think that the differences in pilosity/pubescence are sufficient on the basis of the material examined in this study. At present, we treat all three as distinct species until more material becomes available.

Etymology

The new species was named after “Smaug”, the villain dragon from the fantasy novel "The Hobbit" written by J.R.R. Tolkien. The species epithet is an arbitrary combination of letters.

Material examined

MADAGASCAR: Antsiranana, Parc National Montagne d'Ambre, 12.2 km 211° SSW Joffreville, 12.59639 S, 49.1595 E, 1300 m, montane rainforest, 2.-7.II.2001 (B.L. Fisher, C. Griswold et al.); Fianarantsoa, R.S. Ivohibe, 7.5 km ENE Ivohibe, 22.47 S, 46.96 E, 900 m, montane rainforest, 7.-12.X.1997 (B.L. Fisher); Toamasina, Ambatovy, 12.4 km NE Moramanga, 18.83937 S, 48.30842 E, 1080 m, montane rainforest, 4.-7.V.2007 (B.L. Fisher et al.).